木聚糖酶分子结构与重要酶学性质关系的研究进展

木聚糖是一种多聚五碳糖 ,是植物细胞中主要的半纤维素成分。木聚糖酶是可将木聚糖降解成低聚木糖和木糖的水解酶 ,它在饲料、造纸、食品、能源工业和环境科学上有着广阔的应用前景。随着分子生物学、结构生物学的发展及蛋白质工程的应用 ,对木聚糖酶结构和功能的研究不断深入。这里重点阐述与酶的活性、热稳定性、作用pH、等电点、底物亲和性及催化效率等重要性质相关的分子结构研究进展 ,讨论了其进一步的研究发展方向。研究木聚糖酶结构与功能的关系 ,对进一步加深木聚糖酶作用机制的了解、指导木聚糖酶的分子改良有重要意义。

Recent Advances in Structures and Relative Enzyme Properties of Xylanase

Xylanase can hydrolyze xylans into xylooligosaccharides and D xylose, and has great prospect for applications in feed industry, paper and pulp industry, food industry and environment science. The study of xylanase had been started in 1960's.With the development and application of the new technologies, such as molecular biology, structural biology and protein engineering, many progresses have been made in the research of structures and functions of xylanase. This paper reviews the research progress and trend in the structure correlating with the important properties of xylanase. Analyses of three dimensional structures and properties of mutants have revealed that glutamine and aspartic acid residues are involved in the catalytic mechanism.The thermostability of xylanase correlated with many factors, such as disulfide bridges,salt bridges,aromatic interactions,cotent of arginine and proline,and some multidomain xylanase have thermostability domains in N or C terminal.But no single mechanism is responsible for the remarkable stability of xylanase.The isoelectic points and reaction pH of xylanase are influenced by hydrophobicity and content of electric charges.Many researches had demonstrated that aromatic amino acid,histidine,and tryptophan play an important role in improving enzyme substrate affinity.The researches of structures and functions of xylanase are of great significance in understanding the catalytic mechanism and directing the improvement of xylanase properties to meet the application requirement.